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CHAPTER 22 Nuclear Chemistry. I. The Nucleus (p. 701 - 704). I. II. III. IV. B. Nuclear Binding Energy. Energy released when a nucleus is formed from nucleons. High binding energy = stable nucleus. E = mc 2. E: energy (J) m: mass defect (kg) c: speed of light (3.00×10 8 m/s).
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CHAPTER22 Nuclear Chemistry I. The Nucleus (p. 701 - 704) I II III IV
B. Nuclear Binding Energy • Energy released when a nucleus is formed from nucleons. • High binding energy = stable nucleus. E = mc2 E: energy (J) m: mass defect (kg) c: speed of light (3.00×108 m/s)
CHAPTER22 Nuclear Chemistry II. Radioactive Decay (p. 705 - 712) I II III IV
A. Types of Radiation • Alpha particle () • helium nucleus paper 2+ • Beta particle (-) • electron 1- lead • Positron (+) • positron 1+ concrete • Gamma () • high-energy photon 0
parent nuclide alpha particle daughter nuclide B. Nuclear Decay • Alpha Emission Numbers must balance!!
electron positron B. Nuclear Decay • Beta Emission • Positron Emission
electron B. Nuclear Decay • Electron Capture • Gamma Emission • Usually follows other types of decay. • Transmutation • One element becomes another.
B. Nuclear Decay • Why nuclides decay… • need stable ratio of neutrons to protons DECAY SERIES TRANSPARENCY
C. Half-life • Half-life (t½) • Time required for half the atoms of a radioactive nuclide to decay. • Shorter half-life = less stable.
C. Half-life mf:final mass mi:initial mass n:# of half-lives
C. Half-life • Fluorine-21 has a half-life of 5.0 seconds. If you start with 25 g of fluorine-21, how many grams would remain after 60.0 s? GIVEN: t½ = 5.0 s mi = 25 g mf = ? total time = 60.0 s n = 60.0s ÷ 5.0s =12 WORK: mf = mi (½)n mf = (25 g)(0.5)12 mf = 0.0061 g
CHAPTER22 Nuclear Chemistry III. Fission & Fusion (p. 717 - 719) I II III IV
A. Fission • splitting a nucleus into two or more smaller nuclei • 1 g of 235U = 3 tons of coal
A. Fission • chain reaction - self-propagating reaction • critical mass - mass required to sustain a chain reaction
B. Fusion • combining of two nuclei to form one nucleus of larger mass • thermonuclear reaction – requires temp of 40,000,000 K to sustain • 1 g of fusion fuel = 20 tons of coal • occurs naturally in stars
235U is limited danger of meltdown toxic waste thermal pollution fuel is abundant no danger of meltdown no toxic waste not yet sustainable C. Fission vs. Fusion FISSION FUSION
CHAPTER22 Nuclear Chemistry IV. Applications (p. 713 - 716) I II III IV
Cooling Tower A. Nuclear Power • Fission Reactors
A. Nuclear Power • Fission Reactors
A. Nuclear Power • Fusion Reactors (not yet sustainable)
A. Nuclear Power • Fusion Reactors (not yet sustainable) National Spherical Torus Experiment Tokamak Fusion Test Reactor Princeton University
B. Synthetic Elements • Transuranium Elements • elements with atomic #s above 92 • synthetically produced in nuclear reactors and accelerators • most decay very rapidly
C. Radioactive Dating • half-life measurements of radioactive elements are used to determine the age of an object • decay rate indicates amount of radioactive material • EX: 14C - up to 40,000 years238U and 40K - over 300,000 years
Radiation treatment using -rays from cobalt-60. D. Nuclear Medicine • Radioisotope Tracers • absorbed by specific organs and used to diagnose diseases • Radiation Treatment • larger doses are used to kill cancerous cells in targeted organs • internal or external radiation source
E. Nuclear Weapons • Atomic Bomb • chemical explosion is used to form a critical mass of 235U or 239Pu • fission develops into an uncontrolled chain reaction • Hydrogen Bomb • chemical explosion fission fusion • fusion increases the fission rate • more powerful than the atomic bomb
F. Others • Food Irradiation • radiation is used to kill bacteria • Radioactive Tracers • explore chemical pathways • trace water flow • study plant growth, photosynthesis • Consumer Products • ionizing smoke detectors - 241Am